1. Field of the Invention
The present invention relates to an electroconductive member used for an electrophotographic image forming apparatus, a process cartridge and an electrophotographic image forming apparatus.
2. Description of the Related Art
In the electrophotographic image forming apparatus, a charging roller used for a contact charging method is known in which a conductive elastic layer containing an ion conductive agent as a conductive material is formed on the outer periphery of the conductive mandrel. Unfortunately, the conductive elastic layer given conductivity by the ion conductive agent has a problem. Namely, in order to improve the conductivity by the ion conductive agent, a large amount of the ion conductive agent needs to be added to the conductive elastic layer. Moreover, in the case where a large amount of the ion conductive agent is added, the ion conductive agent may bleed out to the surface of the conductive elastic layer under high temperature and humidity. For such problems, Japanese Patent Application Laid-Open No. 2003-012935 proposes use of a quaternary ammonium salt represented by the following formula (14) as the ion conductive agent.
wherein R7, R8, R9 and R10 represent an alkyl group, at least one of these is different from the other, and at least one of these represents an alkyl group having 4 to 8 carbon atoms; n− represents an anion of n valence, and n represents an integer of 1 to 6.
In the disclosure of Japanese Patent Application Laid-Open No. 2003-012935, bleed out of the ion conductive agent to the surface of the conductive elastic layer can be suppressed because in the conductive elastic layer containing the quaternary ammonium salt represented by the above formula (14) as the ion conductive agent, even a small amount of the ion conductive agent to be added can give high conductivity to a conductive elastic layer.